1. Field of the Invention
The present invention relates to an engine cooling structure in which cylinder barrels having cylinder bores and cooling cylinder water jackets are coupled to a crankcase with a crankshaft rotatably supported therein. Cylinder heads are provided having head water jackets communicating with the cylinder water jackets and are coupled to the cylinder barrels with combustion chambers defined between the cylinder heads and the cylinder barrels. Pistons are slidably fitted in the cylinder bores with top ends facing the combustion chambers. A water pump is provided for circulating a coolant between the cylinder and head water jackets and is mounted on the crankcase on one end thereof along the axis of the crankshaft.
2. Description of Background Art
An engine is known wherein a water pump is mounted on an end of a crankcase along the axis of a crankshaft, for supplying a coolant to water jackets of cylinder barrels coupled to the crankcase. See, for example Japanese Patent Laid-open No. 2000-161062.
In the above conventional structure, the water pump and the cylinder barrels are connected by conduits, which supply water from the water pump to cylinder water jackets. In addition, conduits for delivering out the coolant, which flows from the cylinder water jackets into head jackets, are connected to a head cover. Therefore, the coolant piping around the engine is complex. In particular, the coolant piping is more complex if incorporated in a horizontally opposed engine because a pair of conduits for guiding the coolant from the water pump is connected to the water pump and conduits for delivering out the coolant are connected respectively to cylinder heads on both sides of the crankcase.